The basic meaning behind the two terms – Laxative and Purgative – is same. It basically means – to increase the gastrointestinal motility.
If the action is stronger, the word is – Purgative or Cathartic. Purgative action leads to excretion of large amount of liquid stools, also sometimes associated with griping pain.
If the action is mild, the word used is – Laxative (also called Aperient). Its a mild action with excretion of soft, formed stools (less watery), without griping or discomfort.
But many times the words Laxative / Purgative are used interchangeably; because the basic action is stimulating GI motility.
In general, laxatives/purgatives are contraindicated (should not be used) in following situations:
1. Undiagnosed acute abdominal colicky pain with vomiting
2. Bowel obstruction or stricture
3. Constipation related to definitive illnesses like malignancies, drug-induced constipation, hypothyroidism or hypercalcemia
Classify Laxatives/Purgatives with examples.
Laxatives or Purgatives are classified based on their mechanism of action.
- Bulk Laxatives: Dietary fiber (bran), Psyllium, Isapgol, methyl cellulose, Phenolphthalein, Agar agar
- Stimulant Laxatives / Contact purgatives/ Irritant purgatives: Bisacodyl, senna, castor oil, cascara segrada, Sodium picosulfate
- Osmotic or Saline Laxatives/Purgatives: Mg(OH)2 (Milk of magnesia), MgSO4 (epsom salt), Na2SO4 (Glauber salt), Na-K tartrate (Rochelle salt), Lactulose, Polyethylene glycol, Magnesium citrate
- Lubricant or Emollient Purgatives/Laxatives: Liquid paraffin (Mineral Oil or Paraffin Oil), Di-Octyl-Sodium-Sulfo-Succinate (Docusates) (DOSS)
- Chloride channel activators: Lubiprostone, Linaclotide
- Prokinetics: Tegaserod (5HT4 agonists)